1. Field of the Invention
The present invention relates to techniques for adjusting the backlash between the bevel gears and the pinion gears in a bevel-type differential.
2. Description of the Related Art
A typical bevel-type differential has two bevel gears and a plurality of pinion gears, typically four, mounted in a differential housing. If it is a limited slip differential, various clutch and separator plates also are provided between each bevel gear and the housing to clutch the two together. For proper operation, a small amount of play or backlash normally is provided between each bevel gear and the pinion gears. The amount of play typically is adjusted by changing the thickness of a shim between the bevel gear and the housing, or, in the case of the limited slip differential, between the clutch pack and either the housing or the bevel gear.
Due to manufacturing tolerances, the backlash between each bevel gear and the pinion gears normally must be adjusted for each differential by adjusting the thickness of the shim used. In the past, this has been accomplished by placing one of the bevel gears and the clutch pack (if any) in the corresponding half of the differential housing. The pinion gears on the shaft then are placed on top of the housing in the position they will occupy upon final assembly. The pinion gears are then moved back and forth by hand, and a micrometer is used to measure the backlash directly, i.e., to measure how far each pinion gear moves before it engages the bevel gear. The average measured backlash of all the pinion gears is then used to estimate the shim pack thickness required to bring the backlash within design specifications. A shim pack of this size then is added and the process repeated until the appropriate backlash is obtained. The entire process then is repeated with the other bevel gear in the other half of the differential housing. The adjustment and assembly process for the complete differential can take as much as three hours.